1. Field of the Invention
The invention relates to an ignition coil; in particular, the invention relates to an ignition coil that can prevent filled resin from leaking.
2. Description of the Related Art
An ignition coil ignites combustible gas by high voltage. Referring to FIG. 1a, a conventional ignition coil 10 comprises a casing 20, a bobbin 30, a primary coil (not shown), at least one secondary coil (not shown), a circuit (not shown) and a bar core 70. The casing 20 is made of plastic.
The bobbin 30 is disposed inside the casing 20, as shown in FIG. 1a. The bobbin 30 is provided with a primary portion 50 and two secondary portions 60. The primary portion 50 separates the secondary portions 60 by partitions. The primary portion 50 is provided with two terminals 51. Each of the secondary portions 60 is provided with two pins 62.
The primary coil surrounds the primary portion 50 and is electrically connected to the terminals 51. One end of the secondary coil attaches to one of the pins 62, and the other end of the secondary coil attaches to the other pin 62 by solder.
The bar core 70 penetrates the bobbin 30 to provide a magnetic route. The circuit converts a DC voltage to a triggering-voltage signal. The triggering-voltage signal inputs to the primary coil. By the voltage conversion of the primary coil and the secondary coil, the D.C. voltage is converted to a high voltage. The high voltage ignites the combustible gas through the pins 62 in a tip-discharging manner.
The casing 20 is filled with a resin such as an epoxy resin so as to prevent high voltage, as generated by the coil portion, from leaking out of the casing 20 and a dielectric breakdown from being caused in the ignition coil by the high voltage.
FIG. 1b is an enlarged view of the pins 62 in FIG. 1a. During assembly, the pins 62 must pass through holes 25, formed in the casing 20, to expose their tips. As a result, the filled resin can leak out of the casing 20 through the holes 25. Accordingly, a design in which the diameter of the hole 25 is smaller than the diameter of the pin 62 is provided. However, in such design, the wire (not shown), attached to the pin 62, is easily broken when the pin 62 passes through the hole 25, is because the size of the pin 62 is bigger than that of the hole 25 so that the pin 62 is easily squeezed out of the hole and then the wire is twitched by the squeezed pin 62.
Therefore, it is desirable to develop an ignition coil that can prevent the attached wire from breaking and prevent filled resin from leaking while assembling.
In order to address the disadvantages of the aforementioned ignition coil, the invention provides an ignition coil that can prevent filled resin from leaking.
Another purpose of this invention is to provide an ignition coil that can prevent the attached wire from breaking.
Accordingly, the ignition coil of this invention comprises a casing, a plurality of pins and a bobbin. The pins are disposed inside the casing. The bobbin, having a plurality of terminals corresponding to the pins respectively, is disposed inside the casing. Each of the terminals is provided with a ring-shaped portion in contact with the corresponding pin.
Furthermore, each of the ring-shaped portions surrounds the corresponding pin so as to be in contact with the corresponding pin.
Furthermore, each of the terminals is provided with a protruding portion. The bobbin is provided with a primary portion and at least one secondary portion, and the terminals are formed on the secondary portion. The primary portion is provided with another two terminals.
Furthermore, the ignition coil comprises a core disposed inside the bobbin. The casing is made of plastic, and each of the pins is made of metal.